Pituitary Metastasis Clinical Presentation of Diabetes Insipidus Six Years after Invasive Breast Carcinoma Diagnosis: Case Report

Abstract

Introduction: Breast carcinomas are the major cause of death in women with cancer worldwide, mainly in metastatic cases. The pituitary gland stands for only 6-8% of the secondary sites of distant metastasis and it is usually asymptomatic. When symptomatic, these lesions can mimic primary pituitary diseases. Case report: A 43-year-old woman underwent a left mastectomy with axillary lymph node dissection in April 2013 due to a luminal, invasive ductal carcinoma with nodal metastasis. Six years later, she started complaining of myalgia, bone pain, dizziness and decreased visual acuity, in addition to polydipsia and polyuria. Laboratory tests showed hyperprolactinemia and diabetes insipidus suggestive of panhypopituitarism. Magnetic resonance imaging of the brain showed a sellar tumor with extension to adjacent structures which was removed on November 2019. A pathology report of an epithelial neoplasm of unknown origin and an immunohistochemical study showed positivity for estrogen, progesterone receptors and GATA 3, and negativity for pituitary hormones. This set of findings and the histological morphology were consistent with a metastatic mucinous adenocarcinoma of mammary origin without HER-2 overexpression. The patient underwent ovarian ablation, central nervous system radiotherapy, chemotherapy and oncological follow-up. Conclusion: The patient's young age and clinical presentation of visual impairment and sudden development of diabetes insipidus diverges from the current data, since these findings are usually present in asymptomatic women over sixty-years-old. The varied clinical presentation can lead to a delay in diagnosis of pituitary metastasis, which reinforces the importance of reporting cases like this.